There exist many wired digital interface standards for connecting digital devices. These can include, for example, universal serial bus (USB), FireWire and serial peripheral interface (SPI). There also exist physical interfaces which implement these standards. The interfaces may be included in physical devices (such as, for example, keyboards, computer mice, computer cases, mobile telephones, portable audio players, flash drives) which utilize these interfaces to communicate with other devices.
Some interfaces may be synchronous. Synchronous interfaces may require that when two or more interfaces are connected, a clock signal be sent from one interface to one or more of the other connected interfaces. An interface receiving an incoming clock signal may need to detect edges of the incoming clock signal while utilizing a different local clock signal for its electronics. In order to ensure that the edges are properly and timely detected, the interface receiving the clock signal may need to use a local clock signal that is of much higher frequency than the incoming clock signal. This may result in relatively high power dissipation as well as various expenses necessary to generate the high frequency local clock signal.
Furthermore, the requirement of a local clock signal of a significantly higher frequency than the incoming signal may limit the frequency of the incoming signal. Since data transmission may be timed in accordance with the incoming signal this may limit the rate of data transmission of the interface.